[Allergy to local anesthetics].

Patch testing with the local anaesthetics benzocaine and caine mix frequently yields positive reactions. Their relevance with regard to local anaesthesia is not clear. We therefore performed prick and intracutaneous tests with a battery of local anaesthetics in a group on 104 patients with known contact allergic reactions to these substances. Prick testing always yielded negative results. Intracutaneous testing showed also only rare positive immediate and delayed hypersensitivity reactions. In addition, a clear correlation was seen between the sensitizing potential and chemical structure of the local anaesthetics. Substances with amide structure never showed, with the exception of butanilicaine, any positive reaction in contrast to procaine exhibiting an ester structure. From our results, it can be concluded that contact allergic patients can be subjected to injection local anaesthesia without a significant risk of allergic reaction. In addition, the results show the importance of the route of administration for the manifestation of an allergic reaction.